1. Field of the Invention
The invention relates to drive coupled, dual motor, reversible hydraulic drive winding systems, and in particular, to an improved anti-cavitation hydraulic manifold hydraulically coupling the hydraulic inputs and outputs of the respective motors to a reversible source of hydraulic power.
2. Description of the Prior Art
In U.S. Pat. No. 5,546,751 entitled An Anti-Cavitation Manifold for Drive Coupled, Dual Motor, Reversible Hydraulic Drive Systems (the '751 patent), summarizing, the Applicant describes his anti-cavitation hydraulic manifold as being:                “ . . . easily and inexpensively fabricated by drilling a single passageway through a single block of material. The ends of the passageway are then enlarged and threaded forming two high-pressure input/output (I/O) chambers adapted for coupling to two conventional hydraulic lines connectable to a reversible source of hydraulic power. Conical valve seats are machined into each end of the passageway opening into each of the enlarged input/output (I/O) chambers. A shuttle rod with a polygonal cross-section is introduced into the passageway connecting between the chambers, and a shuttle ball having a diameter greater than the passageway is placed in each enlarged input/output chamber. Each input/output (I/O) chamber includes a stop for confining the shuttle ball within the chamber. A common bypass passage is drilled through the block of material intercepting the passageway between the enlarged input/output (I/O) chambers establishing the bypass line for the two reversible motors. Two separate ports, each perpendicularly drilled into one of the enlarged input/output (I/O) chambers are threaded for coupling to the respective separate input/output lines of the reversible motors. The remaining input/output lines from the reversible motors hydraulically couple at each end of the bypass passage.” [See Column 3, ll. 40-63, emphasis. added]        
The Applicant specifies in the '751 patent specification with regard to the stops, at Column 6, ll. 62-67:                “Stops 22, preferably small diameter removable threaded rods, penetrate through a side face 44 of the manifold block 12 into the respective input/output chambers 14 & 16 for confining the steel shuttle balls 21 within the respective input/output chambers 14 & 16.Referring to the schematic diagrams shown in FIGS. 1 & 3, the Applicant further observes at Column 7, lines 49-62 of the patent specification, that:        “For optimization, the hydraulic circuit may also include a flow restrictor 59, with a check valve bypass 61 incorporated into the respective input/output lines 29 & 31. However, as a practical matter the skilled hydraulic designer should recognize that the functional properties of such flow restrictor 59 and check valve bypass 61 are inherently provided by the shuttle balls 21 within the I/O chamber 14 & 16 being alternately positioned at their respective stops 22 (flow restriction), or seated upon their respective valve seats 18 (flow restriction bypass). Accordingly, it is possible to optimize the hydraulic circuit by adjusting the ratios of the respective diameters of the I/O chambers 14 & 16, the shuttle balls 21 and the stops 22.Finally in claim 19 of the '751 patent the Applicant describes the means for retaining the balls within the respective input/output (I/O) chambers of claims 17-1, 17-2, & 17-3 as comprising:        “ . . . a pin penetrating into the each input/output (I/O) chambers confining the ball proximate the annular valve seat.” [Column 16, lines 41-45]        
To the extent it is relevant to, and/or bears upon the discoveries and inventions herein set-forth, Applicant's U.S. Pat. No. 5,546,751 filed Oct. 14, 1994 and issued Aug. 20 1996 entitled ‘An Anti-Cavitation Manifold for Drive Coupled, Dual Motor, Reversible Hydraulic Drive Systems’ (the '751 patent) and the patents of Applicant referred to therein are incorporated by reference into this provisional patent application as though fully set forth at length at this point.
Schematically shown in FIG. 1, the anti-cavitation manifold described in the '571 patent performs as described if correctly installed with the high pressure input/output hydraulic line 24 from a reversible source of hydraulic power is coupled to the axial port 23. However, when the manifold is inadvertently incorrectly installed, schematically shown in FIG. 2, where the high pressure input/output hydraulic line 24 from a reversible source of hydraulic power is coupled to the perpendicular port 29 communicating into input/output (I/O) chamber 14, rather than the axial port 23 of I/O chamber 14, the hydraulic system unpredictably fails, locking or freezing the mechanical winding and unwinding components in place. (In such a mix-up, hydraulic line 26 incorrectly coupled to the axial port 23 of I/O chamber 14 connects to an input port of the driven reversible hydraulic drive 2 on the return side of the hydraulic loop.)
Such incorrect coupling of the hydraulic line 24 typically results from installer unfamiliarity or error. When the connection error is discovered (typically following an unexplained failure of the system to properly function sometime after installation) the hydraulic lines 24 & 26 must be disconnected and re-connected correctly to the manifold with an inevitable spillage of hydraulic liquid.
Analysis of the problem, revealed that the failure was attributable to the relative locations of the pin stop 22 and the port 29 perpendicularly penetrating into the input/output (I/O) chambers via the side face of the manifold 12. Simply stated, the port 29 was located between the pin and the annular valve seat at the base of the I/O chamber 14 (See FIGS. 1, 2a-c & 5 of the '751 patent) allowing hydraulic liquid flow from the incorrectly connected the input/output or power side of the hydraulic loop line from the reversible power source 46 to sometimes entrain the steel shuttle ball 21 in I/O chamber 14 trapping it against the stop 22, preventing it both from translating the shuttle rod 19 and seating on its annular valve seat 18 locking the system up.
Also, it was discovered during testing that, because of gravity, if the incorrectly connected manifold of the '751 patent was oriented or mounted such that the pin stop 22 was vertically below the shuttle ball, such that the shuttle ball rests against the pin rather than the protruding end of the shuttle rod, when the chamber 14 is not receiving driving hydraulic power from source of hydraulic power, the sporadic failures of the system and lock-ups were exacerbated.